| | 1 | Author
| J. Wąsicki, Z. Pająk, A. Kozak | Requires cookie* | | | Title
| Cation and Anion Reorientation at Phase Transition in Pyridinium Tetrafluoroborate  | | | | Abstract
| Temperature dependences of and 19 F second moment and spin-lattice relaxation times for polycrystalline pyridinium tetrafluoroborate were measured. A phase transition was discovered at 202 K. A model of cation reorientation between inequivalent (low-temperature phase) and equiva-lent (high-temperature phase) equilibrium positions is proposed. Whether the anion reorients isotropically or about a symmetry axis cannot be decided. An analysis of cross-relaxation effects yielded activation parameters for cation and anion reorientation. The rotational correlation times for both ions converge just at the phase transition reaching the value of 10~ 10 s. | | | |
Reference
| Z. Naturforsch. 45a, 33—36 (1990); received August 5 1989 | | | |
Published
| 1990 | | | |
Keywords
| NMR, cross-relaxation, molecular motions, phase transitions | | | |
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| ZNA-1990-45a-0033 | | | | Volume
| 45 | |
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